Multiple files upload with Rails 3 and paperclip on heroku - ruby-on-rails

Question

I need an interface on my Rails 3 app to upload multiple files to Amazon S3 (because i'm on heroku), possibly with progress bars.
I've easily managed how to set up paperclip and upload single files, but i'm really lost now on how to go ahead.
Please can you give me some advices? It's 2 days i'm searching across all the internet, but i can't find a working solution
** EDIT **
I really can't understand... I'm going mad 'cause I'm losing too many hours on this... please help me.
If I try to open the example app cited by Johnny I only get this (and in my app it is the same):
Where is the UI?
Is there something wrong on my browser?
** EDIT 2 **
Here on GitHub you can find my testapp... please can you explain me why the damn upload UI is not showing up? Thanks!
** EDIT 3 **
Thank you very much Johnny, i wasn't aware of the fact that jquery and prototype can't live together.
Now the plugin is showing up correctly, but as a try to upload something it creates a new "upload" record, but its attachment field is blank, and the files are not on s3.
This is what the console is saying:
Started POST "/uploads" for 127.0.0.1 at 2011-06-27 16:17:22 +0200
Processing by UploadsController#create as JSON
Parameters: {"utf8"=>"✓", "authenticity_token"=>"GesRBTiZR1f2LV/bAeAdxWqF++gxcDJw4pPGStYGsH8=", "upload"=>{"attachment"=>[#<ActionDispatch::Http::UploadedFile:0x000001032834b8 #original_filename="animal-tiger-66550.jpg", #content_type="image/jpeg", #headers="Content-Disposition: form-data; name=\"upload[attachment][]\"; filename=\"animal-tiger-66550.jpg\"\r\nContent-Type: image/jpeg\r\n", #tempfile=#<File:/var/folders/Qj/QjEqvUUNGTmuki5SXOaaG++++TI/-Tmp-/RackMultipart20110627-1818-1syiex9>>]}}
AREL (0.5ms) INSERT INTO "uploads" ("attachment", "created_at", "updated_at", "attachment_file_name", "attachment_content_type", "attachment_file_size", "attachment_updated_at") VALUES (NULL, '2011-06-27 14:17:23.049136', '2011-06-27 14:17:23.049136', NULL, NULL, NULL, NULL)
[paperclip] Saving attachments.
Completed 200 OK in 64ms (Views: 4.2ms | ActiveRecord: 0.7ms)

Answer 1

You can look at jQuery-File-Upload. Demo here and rails 3/Paperclip setup here.
Edit: As #apneadiving mentioned, the library has been updated to version 5. The script you have is for verison 4. You should try modifying this to work with PaperClip. Copy-pasting the majority of the example code into my app (with a few modifications) worked for me:
#app/public/javascripts/application.js
$(function () {
// Initialize the jQuery File Upload widget:
$('#fileupload').fileupload();
// Load existing files:
$.getJSON($('#fileupload form').prop('action'), function (files) {
var fu = $('#fileupload').data('fileupload');
fu._adjustMaxNumberOfFiles(-files.length);
fu._renderDownload(files)
.appendTo($('#fileupload .files'))
.fadeIn(function () {
// Fix for IE7 and lower:
$(this).show();
});
});
// Open download dialogs via iframes,
// to prevent aborting current uploads:
$('#fileupload .files a:not([target^=_blank])').live('click', function (e) {
e.preventDefault();
$('<iframe style="display:none;"></iframe>')
.prop('src', this.href)
.appendTo('body');
});
});
#app/controllers/uploads_controller.rb
def create
#upload = Upload.new(params[:upload])
if #upload.save
render :json => [{
:pic_path => #upload.attachment.url.to_s ,
:name => #upload.attachment.instance.attributes["picture_file_name"]
}], :content_type => 'text/html'
else
render [:json => { :result => 'error'}], :content_type => 'text/html'
end
end
#app/views/uploads/new.html.haml
%link#theme{:href => "http://ajax.googleapis.com/ajax/libs/jqueryui/1.8.13/themes/base/jquery-ui.css", :rel => "stylesheet"}
= stylesheet_link_tag 'jquery.fileupload-ui'
#fileupload
= form_for Upload.new, :html => { :multipart => true } do |f|
.fileupload-buttonbar
%label.fileinput-button
%span Add files...
= f.file_field :attachment, :multiple => true
%button.start{:type => "submit"} Start upload
%button.cancel{:type => "reset"} Cancel upload
%button.delete{:type => "button"} Delete files
.fileupload-content
%table.files
.fileupload-progressbar
%script#template-upload{:type => "text/x-jquery-tmpl"}
%tr{:class => "template-upload{{if error}} ui-state-error{{/if}}"}
%td.preview
%td.name ${name}
%td.size ${sizef}
{{if error}}
%td.error{:colspan => "2"}
Error:
{{if error === 'custom_failure'}}Custom Error Message
{{else}}${error}
{{/if}}
{{else}}
%td.progress
%div
%td.start
%button Start
{{/if}}
%td.cancel
%button Cancel
%script#template-download{:type => "text/x-jquery-tmpl"}
%tr{:class => "template-download{{if error}} ui-state-error{{/if}}"}
{{if error}}
%td
%td.name ${name}
%td.size ${sizef}
%td.error{:colspan => "2"}
Error:
{{if error === 1}}File exceeds upload_max_filesize (php.ini directive)
{{else}}${error}
{{/if}}
{{else}}
%td.preview
{{if thumbnail_url}}
%a{:href => "${url}", :target => "_blank"}
%img{:src => "${thumbnail_url}"}/
{{/if}}
%td.name
<a href="${url}"{{if thumbnail_url}} target="_blank"{{/if}}>${name}
%td.size ${sizef}
%td{:colspan => "2"}
{{/if}}
%td.delete
%button{"data-type" => "${delete_type}", "data-url" => "${delete_url}"} Delete
Edit
Had a quick look at your app, the problem is that you are mixing prototype with jquery. The easiest way around this is to switch to jQuery using jquery-rails.
#Gemfile
gem 'jquery-rails'
Next, run bundle install and then rails g jquery:install.
Then change your app/views/layouts/application.erb to this:
<%= stylesheet_link_tag :all %>
<%= csrf_meta_tag %>
<%= javascript_include_tag 'jquery.min' %>
<%= javascript_include_tag 'jquery-ui-1.8.13.custom.min' %>
<%= javascript_include_tag 'jquery.tmpl.min' %>
<%= javascript_include_tag 'jquery.iframe-transport' %>
<%= javascript_include_tag 'jquery.fileupload' %>
<%= javascript_include_tag 'jquery.fileupload-ui' %>
<%= javascript_include_tag 'jquery_ujs' %>
<%= javascript_include_tag 'application' %>
Note that I removed the
<%= javascript_include_tag :defaults %>
So that I can specify the order in which jquery, jquery_ujs, and application are loaded.

Answer 2

I've begun with a very similar task recently, and the swf plugin (at least the more recent one) will indeed let you update paperclip's record. It has callbacks for just about everything you'd need to extend.
:onUploadComplete (upload_options,event)
Here's Nathan Colgate's gist on the matter. He just makes a remote call to the rails server once the upload is finished telling it of the locations for the paperclip attachment.
from his uploadCompleteHandler
var uploadCompleteHandler = function(upload_options,event){
$.ajax({
url: '<%= notify_rails_of_successful_upload_path(:format => :js)%>',
global: false,
type: 'POST',
data: ({
'authenticity_token' : '<%= form_authenticity_token %>',
'upload' : {
'file_file_name' : upload_options.FileName,
'file_file_size' : upload_options.FileSize,
'file_content_type' : upload_options.ContentType
}
}),
dataType: 'script'
}
)
};
I'm not sure if this exact callback gets triggered for each file; it definitely looks like it would. But he passes everything paperclip needs back through an ajax request. filename,size,content-type. This way all that gets sent to heroku is some text about the file, sparing your app a good amount of work by giving it to the client.
edit: flash is the only way I've found to avoid sending a lot of data through heroku to s3. There are a few html5/js-only uploaders that might be able to get the job done, but the ones I have found are still pretty ripe on the dev tree.

Answer 3

As per Heroku support, see this.
Paperclip & multiple files upload, although not S3 specific.

Answer 4

View: (notice the array blog_post[avatars][])
<form accept-charset="UTF-8" action="/blog_posts" enctype="multipart/form-data" id="new_blog_post" method="post">
<div style="margin:0;padding:0;display:inline">
<input name="utf8" type="hidden" value="✓" />
<input name="authenticity_token" type="hidden" value="<%=form_authenticity_token %>" />
</div>
<p><input id="blog_post" name="blog_post[avatars][]" type="file" multiple /></p>
<p><input name="commit" type="submit" value="Upload" /></p>
</form>
Controller:
# POST /blog_posts
# POST /blog_posts.json
def create
#blog_post = BlogPost.new(params[:blog_post])
#blog_post.avatars.each do |avatar|
each_blog_post = BlogPost.new
each_blog_post.avatar = avatar
if each_blog_post.save
end
end
end
Model:
class BlogPost < ActiveRecord::Base
attr_accessible :title, :avatar, :avatars
has_attached_file :avatar
attr_accessor :avatars
end